fix test_basic_indexing

Author: brokkoli71

src/zarr/core/buffer/core.py

@@ -140,7 +140,7 @@ def __setitem__(self, key: slice, value: Any) -> None:
         self._value = value
 
     def __array__(
-        self, dtype: npt.DTypeLike | None = None, copy: bool | None = None
+        self, dtype: npt.DTypeLike | None = None, copy: bool | None = True
     ) -> npt.NDArray[Any]:
         return np.array(self._value, dtype=dtype, copy=copy)